Ios Swift字符串上的范围运算符（..<；和…）

有人能解释一下为什么在Swift 3中，半开和闭区间对字符串的作用不再相同吗

此代码适用于：

var hello = "hello"
let start = hello.index(hello.startIndex, offsetBy: 1)
let end = hello.index(hello.startIndex, offsetBy: 4)
let range = start..<end   // <-- Half Open Range Operator still works
let ell = hello.substring(with: range)

var hello=“hello”
让start=hello.index（hello.startIndex，offsetBy:1）
让end=hello.index（hello.startIndex，offsetBy:4）
让范围=开始..

为什么
let range=start..要执行您试图执行的操作，请不要调用
子字符串（使用：）
。直接下标：

var hello = "hello"
let start = hello.index(hello.startIndex, offsetBy: 1)
let end = hello.index(hello.startIndex, offsetBy: 4)
let ello = hello[start...end] // "ello"

Cannot convert value of type 'ClosedRange<String.Index>' (aka 'ClosedRange<String.CharacterView.Index>') to expected argument type 'Range<String.Index>' (aka 'Range<String.CharacterView.Index>')

var hello = "hello"
let start = hello.index(hello.startIndex, offsetBy: 1)
let end = hello.index(hello.startIndex, offsetBy: 4)
let range = start..<end   // <-- Half Open Range Operator still works
let ell = hello.substring(with: range)

var hello = "hello"
let start = hello.index(hello.startIndex, offsetBy: 1)
let end = hello.index(hello.startIndex, offsetBy: 4)
let range = start...end   // <-- Closed Range Operator does NOT work
let ello = hello.substring(with: range)   // ERROR

var hello = "hello"
let start = hello.index(hello.startIndex, offsetBy: 1)
let end = hello.index(hello.startIndex, offsetBy: 4)
let ello = hello[start...end] // "ello"